Fan hub construction



Feb. 18, `1941. Af| BARRETT I 2,232,670y

' FANHUB consTRUc'rIoN Filed Aug. 25, 1938 2 Sheets-Sheet 1 Feb. 18, 1941. A. 1.-. BARRETT 2,232,670,

FAN HUB CONSTRUCTION Filed Aug. 25, 1958 `2 sheets-'sheet 2 Patented Fei. 1s, 1941 l Arthur Lee Barrett, Mount Lebanon, Pa.

Application August 25, 1938, Serial No. 226,715

7 claims.

The invention relates generally to propeller type fans, andmore particularly to an improved fan hub construction especially adapted for adjustable blade propellers used in Ventilating fans.

Prior fan hub constructions have required welding or permanently securing substantially all of the hub parts together when the blades are assembled therein, so that it is very ,difficult to adjust the pitch of the blades, and the blades cannot be removed without dismantlingthe whole'tail section of the fan.

Moreover, certain prior hub 4constructions utilize a polygonal or non-circular hub housing or fairing which does not conform to the outer contour of the nose and tail of the fan, and lconsequently creates turbulence in the air stream.

It is therefore an object of the present invention to provide an improved hub construction having a fairing which conforms to the outer contour of the nose and tail sections of the fan, making a smooth inner fairing which creates a minimum of turbulence and friction losses' in the air stream.

Another object is to provide a hub construction for quickly and easily adjusting the pitch of the propeller blades secured therein.

Another object is to provide a hub construction enabling easy removal of one or more of the propeller blades without disturbing other parts of the fan.

A further object is to provide an improved hub construction for adjustably mounting the propeller blades in such a way that the portion between the shank and the inner endof each blade proper is within the hub fairing. l

Another object is to provide an improved hub construction adapted for mounting a variable number of propeller blades.

A still further object is toprovide a hub con- I ample herein, and which is defined in the appended claims.

The invention may be stated generally as in cluding two circular plates mounted on the propeller shaft in axially spaced relation, and one lplate being secured and the other plate movably mounted on the shaft, circular grooves or keyways in the opposing faces of said plates and separable shank socket members secured one part in one plate groove and the other part in the other plate groove for clamping around the blade shanks when the plates are drawn toward each other, and a 1 cylindrical hub housing or fairing through` which the propeller blades project, the movable plate being accessible from within the adjacent tail section of the inner fairing.

Referring to the drawings forming part hereof, in which a preferred embodiment of the invention is shown by way of example,

Figure 1 is a longitudinal view of a propeller type Ventilating fan, showing the outer duct or fairing and the inner nose in section;

Fig. 2 is an enlarged sectional view of the improved hub construction, showing two of the propeller blades in elevation;

Fig. 3 is a transverse sectional view thereof, as on line 3 3, Fig. 2;

Fig. 4 is a fragmentary sectional view as on line as on line 1 1, Fig. 2, looking in the opposite direction from Fig. 3.

Similar numerals refer to similar parts through out the drawings.

The improved hub construction is shown in the drawings as applied to a Ventilating fan of relatively large diameter, but it will be understood that ably made up of several adjoining sheet metal sections secured together in a suitable manner.

The inner falring preferably includes a hollow nose section 8 and a hollow tail section 3, which may be tapered to a point at the discharge end of the inner fairing in a usual fashion, as shown, and the nose and tail are circular in cross section. The housing or fairing I of the hub for the propeller blades is cylindrical according to the present invention, having the same diameter as the adjacent portions of the nose and tail section and conforms thereto in contour, so that the hub housing I0 forms a smooth inner fairing with the nose and tail sections.

The tail section 3 may be supported at its discharge end on the flared portion 1 of the outer fairing by radial members I I in usual manner. At its other end, the tail section 3 preferably includes a cylindrical portion I2 which is connected to the cylindrical portion I3 of the outer fairing 3 by means of a series of radially extending straightener vanes I4.

'Ihe vanes I4 may be three or more in number, and are preferably streamlined, that is, rounded at the front and rear edges, so as to offer little resistance to the .air now between the outer and inner fairings. These vanes I4 are preferably designed to have a straightening eilect on the whirling air stream which is set up by the propeller blades.

The nose section 3 preferably houses a propeller shaft I5 coaxial with the inner fairing which is formed by the nose section 3, housing I Il and tail section 3. The shaft I8 may have a pulley I6 thereon adapted to be driven by a belt I1, although other driving means may be provided without departing from the invention.

Preferably the belt I 1 extends through a radially extending hollow belt housing I8 which passes through the wall I3 oi? the outer duct. being supported exteriorly of said duct wall I3 on a suitable base indicated at 2li. The duct housing I3 provides means for shielding the belt I1 which preferably extends through theouter duct wall I3 for connection with suitable power drive means. and the ends of the duct I8 within the nose 8 at opposite sides of the pulley I3 are adapted to support shaft bearings 2I.' Preferably the belt housing I8 is streamlined or rounded at its front and rear edges so as to offer a minimum of resistance to the air ilow through the outer duct.

Obviously, the propeller shaftmay be directly connected to a driving motor located within the nose section 8, if desired.

A series of circumferentially arranged propeller blades 22 are mounted between the nose section 8 and the cylindrical portion I2 of the tail section 3 for being driven by the propeller shaft I5. The hub assembly of the propeller preferably includes a collar 23 secured on the tapered end 24 of the propeller shaft I 5 by means of a key 25, a nut 23 being screwed on the end of the propeller shaft to wedge the collar 23 axially on the tapered portion 24'of the propeller shaft.

A circular hub plate 21 is axially'mounted on the collar 23 at its front or entrance end, and a series of strengthening gussets 23 may be provided, being welded to the plate 21 and the collar 23 as indicated in Fig. 2, for rigidly securing the plate 21 on the propeller shaft.

A circular hub plate '23 is movably mounted axially on the shaft collar 23 at its :rear or discharge end so as to be axially spaced from the nxed hub plate 21, the plates 21 and 23 being of the same diameter.

The inner or opposing faces of the hub plates 21 and 23 are provided with registering circular grooves or keyways 33 and 3l respectively. Means for clamping the shanks of the propeller blades preferably includes a two part clamping collar or socket for each shank, one part 32 being secured to plate 21 and the other part 33 being secured to plate 23. The socket parts 32 and 33 are provided with curved ribslor projections 34 and 3l for fitting in the opposing grooves 30 and 3I respectively. Also, the parts 32 and 33 are provided with inner half cylindrical bores 38 and 31 respectively, arranged to extend radially of the hub plates when secured therein, for mating and fitting around the reduced shanks 38 of the propeller blades. As shown, the portion 22t of each blade which connects itsinnermost working section with its shank provides a relatively gradual transition therebetween.

Preferably the inner ends of said shanks 38 are provided with circular flanges 33 received in recesses formed by mating semi-circular recesses in the socket parts 32 and 33, for holding the propeller blades against radially outward movement. Straps 43 are provided abutting the radially inner surfaces of flanges 33, being secured to the socket parts 32 and 33 by screws 4I, for holding the propeller blades from moving radially inward during adjustment thereof.

'I'he socket parts 32 and 33 are preferably secured in position in the grooves 33 and 3| respectively by means of screws 42 extending through the plates 21 and 23 and screwed into the collar parts.

Means for drawing up plate 23 for moving it toward plate 21 to clamp the socket parts 32 and 33 around the blade shanks 38 preferably includes a series of clamping bolts 43, which may consist of two bolts extending'through the hub plates and each of the clamping collar parts, one bolt at each side of each blade shank 33.

It will be apparent that if greater strength is desired or required in the hub to resist the centrifugal force on the propeller blades, the

depth of the circular keyways 30 and 3I and the interfltting ribs 34 and 35 on the sockets may be increased, or additional keyways and socket parts may be provided for securing extensions of the blade shanks.

'Ihe hub housing I0, which forms part of the inner fairing, is preferably constructed in cylindrical segments los, one for each propeller blade 22. 'I'hese segments are preferably secured to the peripheral edges of the plates 21 and 23 by screws 44, and each segment has a slot 45 through which a blade 22 passes at its innermost portion. 'I'he slots 43 substantially conform to the cross sections of the blades at their radially inner ends, but are enough larger to permit adjusting the pitch of the blades between their maximumand minimum requirements.

In assembling the improved hub construction in the Ventilating fan shown in the drawings, the

' blades are first assembled in the hub, and then the entire hub assembly is mounted on the propeller shaft I5. Preferably, this is accomplished by first securing the socket parts 32 in their respective positions in keyway 33 of hub plate 21 which is nxed on the shaft collar 23, by means of cap screws 42. Similarly thel socket parts 33 are secured in position In the keyway 3| of movable hub plate 23 by cap screws 42. In both cases the cap screws are not fully tightened, so

that the sockets can be adjusted slightly when assembled.

Next the propeller blades 22vare positioned with' over the blades and secured to the edges of the hub plates 21 and 2s by tightening the screws 44, and the hub assembly is then mounted on the propeller shaft l5 by wedging the shaft collar 23 onto the tapered portion 24 of the drive shaft, and the nut 26 tightened.

If it is desired to adjust the pitch of the blades' after the fan is assembled, access to the movable plate 29 at the rear side of the hub may be had through a hatchway 46 provided in the tail section 9 of the inner fairing. Thus the nuts on vclamping bolts 43 may all be loosened sufficiently to allowl the blades 22 to be turned in their sockets formed by the socket parts 32 and 33, permitting adjustment of the pitch of the blades, after which the clamping bolts are again tightened. During this adjustment, the straps 40 prevent radially inward movement of the blades.

If it is desired to remove one or more of the blades, this vcan b e accomplished by loosening the clamping bolts 43 and moving plate 29 rearwardly a sufficient distance so that the blades can be withdrawn radially, and thus the blades can be removed without disturbing the other parts of the fan, as for instance dismantling the varies I4 and tail section 9.

The improved hub construction is adapted for mounting a variable number of propeller blades, asfor instance in the example shown, alternate blades can be removed to provide a three-bladed propeller instead of a six-bladed propeller.v Moreover, by relocating the bolt and screw holes-in the plates 21 and 29, a diiferent number of propeller blades can be secured in socket parts in the keyways 30 and 3 I, so that for example a fou'r-bladed Since the blade sections 22 extend through the 1 slots 45 in the hub fairing segments ills, the transitlon portion 22t from the last working section of the blade proper to the blade shank is out of the air stream, thereby greatly reducing turbulence in the air stream. Furthermore, the transition from the blade to the shank may be made relatively gradual so as to reduce the stress concentration at any one point and increase lthe effective strength of the blades. Due to this fact, the blades may be made of light weight metal such as aluminum alloy in order to meet certain requirements. v

'I'he improved hub construction is simple, compact and easily assembled, and provides asmooth inner fairing which enables producing a fan of high eillciency.

I claim:v 1. Fan hub construction including a propeller shaft, a hub plate xed on said shaft coaxial therewith, a hub plate axially movably mounted on said shaft coaxial therewith and in axially spaced relation to said fixed hub plate, saidl hub plates embodying the mounting means for mounting the propeller blades on the shaft, the opposing faces ofsaid hub plates havingv registering grooves, socket parts removably secured in said grooves and mating to form radially extending sockets, propeller blades having shanks fitting in said sockets, and means clamping the hub plates to-z gether and the blade shanks inthe sockets.

2. Fan hub construction including a propeller shaft, afhub plateflxed on said shaft coaxial therewith, a hub plate axially movably mounted on said shaft coaxial therewith and in axially spaced relation to said xed hub plate, said hub4 plates embodyingthe mounting means for mounting the propeller blades on the shaft, the opposing faces of said hub plates having registering grooves, socket parts secured in said grooves and mating to form radially extending sockets, a cylindrical hub housing secured to the peripheral edges of said hub plates, propeller blades extending through said'hub housing and having shanks tting in said sockets, and means clamping the hub plates together and the blade shanks in the f sockets.

3; Fanv hub constructionA including a propeller shaft, axially spaced hub plates non-rotatably mounted on said'shaft for relative axial movesecured in the opposing surfaces of said hub plates, radially extending propeller blades jmounted in said sockets for being rotated by said shaft, a hub housing secured to the peripheries of said hub plates and comprising cylindrical seg-k i ments fitting loosely one over each propeller blade,

and means clamping the hub plates together and4 the blades in thesockets.

' 4. Fan hub construction including a propeller 25- ment with respect to each other, separable sockets secured in the opposing surfaces of said hub plates.,` a cylindrical hub fairing secured to the peripheries of said hub plates and comprising cylindrical segments, propeller blades extending radially one through each hub segment and having reduced shanks fitting in: said sockets forbelng rotated by said shaft, the transition portion of each blade connecting its innermost working section and shankbeing within the hub fairing, and means clamping the hub plates and sockets together. l

5. In a fan having an inner fairing including a hollow nose section 1and 'a` hollow4 tail section, a propeller shaft in said `nose section and coaxial therewith, a fa'n hub between said nose and tail sections and having a housing conforming thereto, axially spaced hub plates in said hub housing `mounted `on said propeller shaft for relative axial movement, separable sockets secured in the op- -posing surfaces of said hub plates, propellerl blades plates together and accessible from within said tail section whereby one of said hub plates may be moved away from the other to permit adjusting the pitch of the propeller blades.l

6. In a fan having an outer fairing-and a hollow inner fairing, a propeller shaft mounted in the inner fairing coaxial therewith, a hub plate xed on said propeller shaft, a second hub plate movable axially on said propellerl shaft and axially spaced from said fixed hub plate, separable sockets secured in the opposing surfaces of said hub plates, a hub fairing secured to theperipheries of said hub plates coaxial with and conforming in contour to said inner fairing, propeller blades exlo hub plates one mounted immovably on said collar and the -Iother arranaed tor relative axial movement on said collar with respect to the tirst hub plate, separable sockets removably secured in the opposing surface of said hub plates, propeller blades removably mounted in said sockets and 5 terminating short of said collar, and means clampin: the hub plates together to clamp the blades in said sockets.

ARTHUR `LE!! BARRETT. 

